Construction of land masses bounded by water

ABSTRACT

A LAND MASS, SUCH AS AN ISLAND, JETTY, OR THE LIKE IS CONSTRUCTED IN A BODY OF WATER BY EXPLOSIVELY MOUNDING THE WATER BODY FLOOR TO FORM A MASS OF BROKEN ROCK, OR SOCALLED RETARC (INVERT CRATER) RISING ABOVE THE WATER SURFACE.

March 9, 1971 l M. A. LEKAs 3,563,449

CONSTRUCTION 0F LAND MASSES BOUNDED BY WATER Filed Oct. 2. 1969 ATTORNEY United States Patent O U.S. Cl. 61--35 2 Claims ABSTRACT OF THE DISCLOSURE A land mass, such as an island, jetty, or the like is constructed in a body of water by explosively mounding the water body floor to form a mass of broken rock, or socalled retarc (invert crater) rising above the water surface.

BACKGROUND OF THE INVENTION The invention disclosed herein was evolved in the course of work performed by the United States Atomic Energy Commission.

Under various circumstances it is desirable to provide land masses rising above the surface of a body of water at locations where such land masses were previously nonexistent. For example, in the off-shore drilling of oil it is the usual practice to construct platforms for the support of drilling rigs. These platforms are exceedingly diflicult, time consuming, and expensive to erect by virtue of the extensive underwater construction involved in the anchoring thereof. Substantial advantages would thus be gained by the rapid and economical construction of islands serving as substitutes for the olf-shore drilling rig supporting platforms. The islands would also beneficially provide tank sites for the storage of oil from the off-shore oil field. Rapidly and economically constructed islands would also possess substantial utility as sites for radar and tracking stations and other defense purposes in vast expanses of water presently devoid of land masses. A need also exists for the economical construction of massive jetties and other sea walls.

Heretofore, mounds of broken rock, or so-called retarcs, have been explosively created on land by detonating an explosive charge emplaced beneath the ground surface. For example, in the Sulky nuclear explosion experiment conducted in December 1964 at the Nevada Test Site by the University of California Lawrence Radiation Laboratory, Livermore, for the United States Atomic Energy Commission, an explosive charge was detonated at an emplacement depth beneath the ground surface predetermined to create a crater. However, the depth of burial Was too `great for effective throwout, and a surface mound, rather than the expected crater, resulted. 'I'he mound was apparently formed by the explosive breaking and moving of rock with a resultant significant increase in the total volume due to the spaces created between the pieces of broken rock. The increase in volume over that of the original rock in place, i.e., bulking factor, was sufficiently large, and the rock shattered by the explosion was not imparted sufficient acceleration to be thrown along ballistic trajectories outside the true blast crater boundary, whereby the crater was overlled above the original ground surface to thus form the mound. Technological data pertaining to the Sulky experiment are set forth in UCRL- 12180, Revision 2, Aggregate Production with Nuclear Explosive, S. M. Hansen and I. Toman, University of California Lawrence Radiation Laboratory, Livermore, Calif., May 12, 1965, and PNE720 Project Sulky, Geologic and Engineering Properties Investigations by R. I. Lutton and F. E. Girucky.

The practicable exploitation of surface mounds ex- ACC plosively formed on land in the foregoing manner has been limited because formation of a mound, as opposed to a crater is diicult to accomplish with high reliability. More particularly, the depth of burial of an explosive charge with respect to the yield thereof, i.e., the scaled burial depth, required for mound formation falls within a relatively narrow critical range. For values of scaled depth less than those within the critical range, a throwout crater is formed by the explosive ejection of rock fragments along ballistic trajectories extending outside of the true crater boundary. For values of scaled depth greater than those within the critical range, the explosion may be fully contained without ground surface effect. Slight departures of the actual yield of an explosive charge from the anticipated, or of the actual depth of burial from that predetermined to provide a scaled depth within the critical range for mound formation may thus result in crater formation, or some other diverse effect. Consequently, the explosive formation of mounds on land for beneficial purposes is limited from an economical standpoint because there is not complete assurance that the desired mound will be created.

SUMMARY OF THE INVENTION The general object of the present invention is to provide for the rapid economical formation of islands, jetties, or other land masses bounded by a body of water.

In the accomplishment of the foregoing, the present invention generally comprises detonating a nuclear explosive of a predetermined explosive yield at a predetermined emplacement depth in the fioor of a body of water at a site having a bulking factor greater than a predetermined minimum and a water depth sutiiciently shallow to permit mounding of the floor to a height rising above the water surface. Unlike the explosive formation of a surface mound on land, the explosive formation of a water bounded land mass in accordance with the present invention may be conducted with substantial assurance that the mass will be formed by virtue of the overburden of the water layer which overlies the detonation site having a pronounced damping effect on the explosive ejection of broken rock. The invention is particularly applicable to the formation of water bounded land masses in areas which include large areas of the continental shelves, inland seas and lakes, and the numerous sea mounts in deeper parts of the oceans.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated in the accompanying drawing, wherein:

IFIG. l is a diagrammatic representation of the emplacement of a nuclear explosive preliminary to the formation of a water bounded land mass in accordance with the construction method of the present invention; and

FIG. 2 is a diagrammatic representation of the resulting water bounded land mass explosively formed in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION As illustrated in the drawing, the present invention provides for the construction of an island 11, or equivalent land mass or mound, which rises from the floor 12 of a body of water 13 to a height h in excess of the water depth D so as to project above the water surface. Formation of such a water bounded land mass by conventional construction methods, such as transporting rock to, and dumping the rock at a desired construction site, is entirely unfeasible from a practical standpoint by Virtue of the prohibitive time and expense involved in handling the required volume of rock, among other factors.

In accordance with the present invention the island 11 is constructed relatively simply economically, and rapidly by explosively mounding the Water body oor 12 to the desired height h extending above the water surface. In this regard, a nuclear explosive charge 14 of predetermined explosive yield W is detonated at a predetermined emplacement depth, or depth of burial (DOB), in the iloor 12 at a construction site whereat the water is of a relatively shallow predetermined depth D and the rock or other medium of the floor has a bulking factor (BF), i.e., increase in volume due to spaces between broken pieces of the medium over the in situ volume of the medium, greater than a predetermined minimum. More particularly, the explosive yield and depth of burial of the charge 14 are predetermined with respect to the water depth and bulking factor commensurate with a scaled depth of burial within a predetermined critical range productive of mounding, and mound proportions of a height in excess of the water depth. Emplacement of the explosive charge 14 is accomplished in a generally conventional manner as by drilling a bore hole 16 in the floor 12 to the predetermined burial depth DOB, lowering the charge to the base of the hole, and stemming the hole with a plug 17 of concrete, rock, or the like to prevent venting of the explosion upon detonation of the charge.

With the charge 14 of predetermined yield W thus emplaced in the -floor 12 of the body of water 13 at the predetermined depth of burial DOB, the charge is detonated. The resulting explosion creates a cavity of radius R and shatters the rock or other medium of the oor above the shot point ZP out to a radius r at the floor surface. The shattered pieces or fragments 18 of the floor medium are ejected from the floor surface to initially form a crater 19 having a boundary of the radius r, and displace the overlying layer of water of depth D. The ballistic trajectories of the ejected fragments lie within the crater boundary, particularly by virtue of the overburden of the water layer having a pronounced damping effect on the acceleration of the fragments. Consequently, the fragments fall back into the crater and, by virtue of bulking of the fragments during fall back, overfill the crater to thereby form the mound or island 11 rising above the surface of the oor 12 to the height h in excess of the depth D of the body of water 13. In this regard, the volume occupied by the fragments is significantly greater than the volume originally occupied by the medium of the floor prior to shattering, due to the interstices existing between the piled fragments. This increase in volume by bulking of the fragments over the original in situ volume, i.e., the Ivolume of crater 19, determines the volume of the island 11. As previously noted, the bulking factor of the medium of oor 12 is greater than a predetermined minimum such that the volume of the bulkedfragments forming the island is sufficient for same to rise above the water surface.

It is particularly important to note that in accordance with the present invention as described above, the island 11, or other water bounded land mass, is formed with relatively high reliability by virtue of the overburden effect of the water layer Which overlies the detonation site. The water layer clamps the explosive acceleration of ejected fragments 18 and thereby tends to constrain same to trajectories that fall within the boundary of crater 19 even runder circumstances where the fragments would otherwise be propelled beyond the crater boundary and hence not refill same to produce mounding. As a result there is a substantially increased latitude in the depth of burial DOB and yield W of the explosive charge 14 for which a mound is created.

It is to be noted that in the construction of an island, or other water bounded land mass, in accordance with the present invention, the previously discussed parameters may be more explicitly related by formulae which are readily derivable from existing explosive mounding data based, for example, on the results of the Sulky nuclear explosion experiment as presented in the hereinbefore referenced reports UCRL-12180, Revision 2, and PNE- 720. More particularly, in the dimensional analysis of the observed effects of undergrohnd nuclear explosions,

it is the usual practice to employ the basic scaling law in which dimensions are proportional to W1/3-4, W being the explosive yield of a detonated charge expressed in kilotons. Accordingly, a scaled depth of burial, DOBS, of the charge is given by:

DOB

where DOB is the actual depth of burial expressed in feet. It has been found that for the explosive formation of a surface mound on land, the scaled depth DOBs is within a critical narrow range of about 200 to 250 ft., and preferably about 210 ft. for optimum effect. Accordingly, the yield, W, and actual depth of burial, DOB, of an explosive charge for opitmum mounding on land are related by:

(l) DOB=210 W1/3.4

It has also been observed from past experience as an approximation, the radius R of the cavity and radius r of the surface boundary of the crater created during the initial stages of the mounding process are related to the actual depth of burial, DOB, by the following:

Moreover, the shapes of the crater and mound have been observed to closely approximate truncated cones.

Thus, based upon the foregoing observations, the volume V of the crater 19, and thus the initial or in situ volume of the rock or other medium of the floor 12 shattered upon detonation of the charge 14, may be expressed as the volume of a truncated cone of base radius R, upper radius r, and height DOB. Therefore,

Consequently, upon substituting the expression for R and r given by Equations 2 and 3 into Equation 4 and simplifying terms, the volume V is related to the depth of burial, DOB, follows:

Similarly, the volume Vm of the mound, or island 11, may be expressed as the volume of a truncated cone having base radius, r, height, h, and an upper radius which has been determined to approximate r/2. Thus,

Simplification and rearrangement of the terms in Equation 6 yields:

7) ,L Vm

From Equation 3, r=DOB. Therefore, substitution into Equation 7 gives:

Since the volume Vm is the increase in the volume V due to bulking of the rock or other medium, the respective volumes are related by the bulking factor (BF) of the medium as follows:

has a bulking factor of at least about 0.4, and typical values range from about 0.4 to about 0.65.

Upon combining Equations and 9 with Equation 8, there is obtained:

hzamno) (BF) (11) D0B=210 w21/3LP However, the weight, P, may be expressed in terms of the water depth P as: (12) UQ "2.6

Where the factor 2.6 is the approximate specific gravity of the medium of floor 12 likely to be encountered.

Substitution of Equation 12 into Equation 11 yields:

Equation 10 may then be combined with Equation 13 and the terms rearranged to give:

W=[0.7(BF ai It will be thus appreciated to construct an island of a desired size in a body of water at a site whereat the water has a given depth and the oor of the water body has a given bulking factor, the yield W and depth of burial DOB of the explosive charge may be readily predetermined in accordance with the foregoing equations, particularly Equations 10, 13 and 14. As an example, assume that it is desired to construct an island that rises about 100 ft. above the surface of a water body at a site Whereat the depth is about 50 ft. and the floor is of consolidated rock having a bulking factor of 0.6. In other words, the island is to be of a height lz of 150 ft. above the floor of the body of water. Substitution of the values into Equation 10 gives:

15020.77 DOB X 0.620.462 DOB Upon solving the foregoing equation, the depth of burial, DOB, is found to be:

DOB=

Thus, it is readily predetermined that an explosive charge with a yield of 5.36KT emplaced about 325 ft. below the surface of the floor of the water body will, upon detonation, generate the desired island rising about ft. above the water surface. In addition, from the previously discussed considerations the radius of the upper surface of the island can be expected to be about half the depth of burial, i.e., about 162 ft.

Although the invention has been described hereinbefore primarily with respect to the formation of an island, it will be appreciated that various modifications and changes may be made without departing .from the true spirit and scope of the invention. For example, an elongated sea Wall or jetty may be constructed by detonating a number of appropriately spaced explosive charges. Thus, it is not intended to limit the invention except by the terms of the appended claims.

I claim:

1. A method of forming a water bounded land mass comprising selecting a site in a body of water whereat the medium of the oor thereof has a bulking factor, BF, greater than a predetermined minimum and the water has a predetermined depth, D, and detonating an explosive charge of an explosive yield, W, and at an emplacement depth of burial, DOB, beneath the surface of said floor both predetermined with respect to said bulking factor and the water depth to mound said floor to a predetermined height, h, in excess of said water depth.

2. A method according to claim 1, further defined by said yield, W, and depth of burial, DOB, being predetermined with respect to said bulking factor, BF, depth, D, and height, h, in accordance with:

h=0.77(D0B) (BF) Where: W is expressed in kilotons, DOB, D and h are expressed in feet, and BF is in a range of about 0.4 to about 0.65.

References Cited UNITED STATES PATENTS 3,291,215 12/1966 Nichols 166-299X 3,303,881 2/1967 Dixon 166--247 3,318,378 5/1967 Coshow 166254 3,342,257 9/1967 Jacobs et al. 166-247 3,404,919 10/1968 Dixon 299-13 THOMAS F. CALLAGHAN, Primary Examiner D. H. CORBIN, Assistant Examiner U.S. Cl. X.R. 102-23 

